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Electrochemical techniques oxidation processes

Chemical and electrochemical techniques have been applied for the dimensionally controlled fabrication of a wide variety of materials, such as metals, semiconductors, and conductive polymers, within glass, oxide, and polymer matrices (e.g., [135-137]). Topologically complex structures like zeolites have been used also as 3D matrices [138, 139]. Quantum dots/wires of metals and semiconductors can be grown electrochemically in matrices bound on an electrode surface or being modified electrodes themselves. In these processes, the chemical stability of the template in the working environment, its electronic properties, the uniformity and minimal diameter of the pores, and the pore density are critical factors. Typical templates used in electrochemical synthesis are as follows ... [Pg.189]

Mital et al. [40] studied the electroless deposition of Ni from DMAB and hypophosphite electrolytes, employing a variety of electrochemical techniques. They concluded that an electrochemical mechanism predominated in the case of the DMAB reductant, whereas reduction by hypophosphite was chemically controlled. The conclusion was based on mixed-potential theory the electrochemical oxidation rate of hypophosphite was found, in the absence of Ni2 + ions, to be significantly less than its oxidation rate at an equivalent potential during the electroless process. These authors do not take into account the possible implication of Ni2+ (or Co2+) ions to the mechanism of electrochemical reactions of hypophosphite. [Pg.256]

R. Kotz reviews the application of the most powerful surface physics technique, photoelectron spectroscopy, for the elucidation of the composition of electrodes. He exemplifies the potential of this technique for materials which play a key role in electrochemical oxidation processes or are used in some other electrochemical process. [Pg.302]

In electrochemical techniques an electrical charge is transfered—electrons are donated by one compound and accepted by another. When a compound donates electrons, the process is called oxidation, when it accepts electrons, the process is called reduction. [Pg.5]

The ligands 369 react with [RuCl2(dmso)4] to yield [RuCl2(dmso)2(369-A, 0)], characterized W spectroscopic and electrochemical methods. Complexes in the families [Ru"(bpy)(370)2] and [Ru" (aca( (370)2] have been reported. The complexes [Ru(bpy)(370)2] undergo a reversible Ru"/Ru" oxidation followed by an irreversible Ru /Ru process the bpy-centered one-electron reduction is also observed. Chemical oxidation of the complexes [Ru(bpy)(370)2] gives [Ru(bpy)(370)2] (isolated as the iodides), the electronic and ESR spectroscopic properties of which have been described. The crystal structure of [Ru(acac)(371)2] has been established, and the electrochemical and chemical redox reactions of [Ru(acac)(370)2] and [Ru(acac)(371)2] generate Ru" and Ru species that have been characterized by spectroscopic and electrochemical techniques. ... [Pg.683]

The peptide fragments of metalloth-ioneins Lys-Cys-Thr-Cys-Cys-Ala [56-61] (FT) were studied by different electrochemical techniques. The cyclic voltam-metric behavior of the peptide fragment in the presence of Cd(II) indicated two reversible electrochemical processes due to the oxidation of the mercury electrode in the presence of CdFT and reduction of CdFT complex, both from the dissolved and adsorbed state [105]. The influence of the experimental conditions on electroreduction of Cd-metallothioneins... [Pg.777]

Energetics of oxidation-reduction (redox) reactions in solution are conveniently studied by arranging the system in an electrochemical cell. Charge transfer from the excited molecule to a solid is equivalent to an electrode reaction, namely a redox reaction of an excited molecule. Therefore, it should be possible to study them by electrochemical techniques. A redox reaction can proceed either by electron transfer from the excited molecule in solution to the solid, an anodic process, or by electron transfer from the solid to the excited molecule, a cathodic process. Such electrode reactions of the electronically excited system are difficult to observe with metal electrodes for two reasons firstly, energy transfer to metal may act as a quenching mechanism, and secondly, electron transfer in one direction is immediately compensated by a reverse transfer. By usihg semiconductors or insulators as electrodes, both these processes can be avoided. [Pg.286]

The great recent development in electrochemical techniques will certainly be helpful for the study of redox processes of a metal which can occur in so many oxidation states. Multinuclear NMR spectrometers will allow increased use of 51V resonance as a routine method for the characterization of complexes in solution. Other recent developments are the study of polynuclear complexes, metal clusters (homo and hetero-nuclear) and mixed valence complexes, and it can be anticipated that these topics will soon become important areas of vanadium coordination chemistry, although the isolation of compounds with such complex... [Pg.456]

Since the electrochemical reduction or oxidation of a molecule occurs at the electrode-solution interface, molecules dissolved in solution in an electrochemical cell must be transported to the electrode for this process to occur. Consequently, the transport of molecules from the bulk liquid phase of the cell to the electrode surface is a key aspect of electrochemical techniques. This movement of material in an electrochemical cell is called mass transport. Three modes of mass transport are important in electrochemical techniques hydrodynamics, migration, and diffusion. [Pg.12]

The N-oxide moiety in heterocyclic amine N-oxidcs, like QDO and PDO, presents a particular electrochemical behavior. On the one hand, the oxygen N-oxide atom could suffer loss of one electron, an oxidation process, and on the other hand, the nitrogen N-oxidc atom, like in nitro compounds or nitrones, could receive one electron in a reduction pathway (Scheme 3). Both processes conduct to different reactive entities that have been studied using different electrochemical and spectroscopic techniques. [Pg.191]

A number of coal-derived liquids were examined by cyclic-voltammetry and other electrochemical techniques and found to show some activity. At anodic potentials films form on glassy carbon electrodes. It is suggested that this film formation is caused by oxidative coupling of radical cationic species with neutral ring structures through a mechanism similar to that which causes charring and coking in coal conversion processes. [Pg.337]

Most descaling and passivation processes for steels were developed prior to the widespread use of electrochemical techniques. As a result, a variety of visual and chemical tests are widely used for determining the surface cleanliness. Chemical tests have also been established to verify the presence of a robust oxide film on austenitic and ferritic stainlesses (8). These methods are very simple to conduct in a manufacturing environment, but they are qualitative in nature and rely strongly on the judgment of the inspector. Outside of the laboratory, electrochemical methods have not been widely used to evaluate cleanliness of carbon and alloy steels after pickling. Nevertheless, they are well suited for this purpose and have been examined in considerable detail in laboratory studies. [Pg.258]

Minerals, electrochemistry of — Many minerals, esp. the ore minerals (e.g., metal sulfides, oxides, selenides, arsenides) are either metallic conductors or semiconductors. Because of this they are prone to undergo electrochemical reactions at solid solution interfaces, and many industrially important processes, e.g., mineral leaching and flotation involve electrochemical steps [i-ii]. Electrochemical techniques can be also used in quantitative mineral analysis and phase identification [iii]. Generally, the surface of minerals (and also of glasses) when in contact with solutions can be charged due to ion-transfer processes. Thus mineral surfaces also have a specific point of zero charge depending on their sur-... [Pg.429]

A method for the preparation of thin films of Fe4[Ru(CN)6]3 ( ruthenium purple ) involving electrochemical reduction of K3[Ru(CN)6] in a solution of Fe2(S04)3 has been developed.28 This ruthenium purple modified electrode is claimed to be one of the best catalysts for evolution of oxygen and chlorine. Electrochemical studies on polyammonium macrocyclic complexes of [Ru(CN)6]4 indicate a 1 1 stoichiometry with a monoelectronic, reversible, oxidation for these complexes this illustrates the control of redox potential of anions by complexation with appropriate receptor molecules.29 The kinetics of oxidation of [Ru(CN)6]4 by [Mn04] in HC104 have been investigated by stopped-flow techniques. It is found that [Ru(CN)6]4" is quantitatively oxidized to [Ru(CN)6]3 in accordance with equation (1) and that two protonated intermediates [RuH(CN)6]3 and [RuH2(CN)6]3 are involved in the oxidation process.30... [Pg.281]


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